Aim: To explore the taxon-dependent contribution of dispersal limitation vs. environmental filters to bryophyte assemblages.

Location: The Thousand Island Lake, China

Taxon: Bryophytes

Methods: We compared the observed beta diversity with the expected values based on six null models (EE, EF, FE, FF, PE, PF) and detected the partial correlation of beta diversity with geographical distances. We quantified the contributions of spatial vs. environmental variables, and island isolation per se to species composition (SC) by using variance partitioning. We modeled the species-area relationships (SARs) for bryophytes and other eight biotas. To explore the taxon-dependent effects of spatial vs. environmental filters on bryophytes, sixteen taxa including five categories (total bryophytes, total mosses, liverworts, acrocarpous and pleurocarpous mosses) and eleven species-richest families were included in the analyses.

Results: The observed beta diversity values were significantly different from the predicted values based on the six null models for all 16 taxa. For all five categories, the observed partial correlations between beta diversity and geographical distance after controlling environmental effects were not only positive but also significantly different from the predicted values based on the null models. Spatial eigenvectors are more important in shaping SC than environmental variables for all 16 taxa except Brachytheciaceae and Anomodontaceae. Spatial eigenvectors contributed more to SC variation in liverworts than in mosses, and in pleurocarpous mosses than in acrocarpous mosses. The effects of island isolation on SC were significant for all five categories and varied highly at the family level. The z-values of the SARs for the five bryophyte categories were all larger than those of the other eight biotas.

Main conclusions: In subtropical fragmented forests, dispersal limitation exerted significant, taxon-dependent effects on bryophyte assemblages. It was dispersal limitation rather than environmental filtering that predominantly regulated SC patterns of bryophytes.